Density-dependent nuclear accumulation of VEGF-D similar to that in cultured cells was observed with fibroblasts in fibrotic areas of human lung suggests that nuclear VEGF-D plays an important role in fibroblast homeostasis In vivo, particularly perhaps in fibrotic lung disease. As VEGF-D processing is known to result from actions of furin and protein conve^rtase (PC)-5, manipulation of VEGF-D processing might produce desirable therapeutic effects on its nuclear trafficking and biological function with potential clinical application.